For example, U.S. Pat. No. 4,679,422, issues to Rubin, et al., discloses a method and apparatus for steady-state measurement of liquid conductivity in porous media. U.S. Pat. No. 6,634,876, issued to Schofield, discloses centrifuges and associated apparatus and methods.
U.S. Pat. No. 6,810,755, issued to Pask, et al., for a permeameter system and method to determine soil hydraulic capacity for onsite wastewater systems. The permeameter has a hollow tube with a second tube slidably disposed within an internal chamber of the hollow tube and is used in combination with one or more tables to correlate a specific rate of reading fall rate of water to the soil hydraulic capacity of the soil being tested. A conventional measuring tape is affixed to the outside surface of the hollow tube such that the numbers extend vertically along the length, or longitudinal central axis, of the hollow tube. The permeameter is used in combination with one or more charts that correspond with soil hydraulic capacity. The charts are created by formulas defined using known soil absorption principals, the dimensions of the permeameter, the dimensions of an auger hole in the soil, and the level of a water line in the auger hole.
Another permeameter is taught in U.S. Pat. No. 6,571,605, issued to Johnson. Johnson teaches a constant-head soil permeameter for determining the hydraulic conductivity of earthen materials, The constant-head soil permeameter is used to determine hydraulic conductivity of earthen materials in a borehole. The permeameter uses includes a calibrated reservoir attached to a suitable length of hose. Water is added to the calibrated reservoir and allowed to flow freely into until an equilibrium level is reached in the borehole and inside the soil permeameter. The water flowing to the permeameter is throttled by buoyant float pressure, thereby allowing better constant head control and much greater depths of testing than previously attained by known permeameters. The permeameter may also include a filtered vent system, backflow check valve, and seals. The filter system restricts entry of soil particles and debris, thereby minimizing cleaning and maintenance of the invention. The soil permeability is determined based on the equilibrium height of water, rate of water flow, and dimensions of the borehole.
Yet another permeameter is taught in U.S. Pat. No. 6,655,192, issued to Chavdar for a combined permeameter-porosimeter that measures normal and lateral permeability measurements on porous materials. The permeability measurements may be taken from compressed or uncompressed samples at room or elevated temperatures. A wide variety of fluids or gas may be used to penetrate the test fluid depending on the application and the porosity of the sample. Briefly, the penetrating test fluid is forced through the sample under pressure and the load, the fluid displacement, and the time are used to calculate the permeability, porosity, pore size distribution, average pore size and the number of pores per unit area.
Finally, U.S. Pat. No. 6,055,850, issued to Turner, et al., teaches a multi-directional permeameter that is used to determine the coefficients of permeability using a constant (or falling) head method for the laminar flow of a fluid (e.g., water), through a specific material or test sample. The apparatus is a mold secured to a base, a lid is secured to the mold, inlet and outlet ports allow fluid flow to occur in both the horizontal plane and the vertical plane to determine the coefficients of permeability of a particular sample either horizontally, vertically, or simultaneously horizontally and vertically.